A host of scouts watched Villarreal take on Eibar on Sunday.
According to Spanish newspaper El Periodico Mediterraneo, Celtic sent scouts to watch Villarreal take on Eibar in La Liga on Sunday.
Villarreal played out a 1-1 draw at El Madrigal over the weekend, with a late goal from left back Jaume Costa rescuing a point for Villarreal after Sergi Enrich's first half opener.
Both teams sit inside the top six in La Liga after impressive starts to the season, and it seems that their players are starting to attract interest.
El Periodico Mediterraneo report that a host of clubs had scouts watching the game, including Atletico Madrid, Ajax, Borussia Monchengladbach, Celta Vigo, Elche, Levante, Genoa, AC Milan, Real Sociedad, Barcelona and Paris Saint-Germain, as well as teams from closer to home.
It's unclear who Celtic were watching, but manager Ronny Deila must be looking to add some new faces to his squad in January, especially at the back.
The Norwegian did snap up Dedryck Boyata and Jozo Simunovic after losing Jason Denayer and Virgil van Dijk, but they have turned in some shaky defensive displays, with fans still wanting another centre back to be snapped up when the transfer window re-opens - and maybe this trip to watch Villarreal against Eibar was to watch a particular defender on show.